IN HIS1930 monograph Civilization and Its Discontents (Das Unbehagen in der Kultur), Sigmund Freud remarked that:

This final phrase, meaning ‘man is a wolf to man’, is a Latin proverb borrowed from Plautus's Asinaria. Although the original meaning is related to the unknown quantity of the stranger (lupus est homo homini, non homo, quom qualis sit non novit ‘man is a wolf and not a man toward a man when he doesn't know what he's like’), today the proverb is often used in the sense employed by Freud, as shorthand to express that humans are often driven by greed and savagery, behaviours deemed typical of wolves.

This metaphor has been in use for over a millennium. A sixth-century Frankish law-code prescribed that a graverobber should be outlawed and declared a wargus, a term which may refer to the malefactor's ‘re-identification […] as a “wolf” or as a thing associated with wolfishness’. Later, the Old Norse cognate of wargus, vargr, meant both ‘wolf’ and ‘outlaw’, and was used of graverobbers and malefactors guilty of other rapacious crimes in both legal and literary contexts. The dual denotation of vargr suggests that the association between abjected criminal figure and wolf was pervasive and culturally ingrained, to the extent that this conceptual similarity became part of the linguistic brickwork of Old Norse. While the Old English cognate of wargus and vargr, wearg ‘criminal’, does not possess a secondary lupine meaning, the English tradition did share this conception of the outlawed graverobber or criminal as wolf-like.

Outlawry as a punishment for behaviours considered proper to wolves was both literal and conceptual. A proclamation of outlawry meant a person was no longer afforded the legal protections enjoyed by other members of the community, forcing them to flee from society until they could pay recompense, or to permanently abandon it upon pain of death.